Self-inking stamp



FIG. 1 is a left perspective view of a self-inking stamp showing my new design;

FIG. 2 is a front elevation thereof;

FIG. 3 is a rear elevation thereof;

FIG. 4 is a right side elevation thereof;

FIG. 5 is a left side elevation thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for a self-inking stamp, as shown. 